Diesel engines are designed to run on a myriad of different fuel sources. At the Exhibition Fair in Paris, France in 1898, Rudolf Diesel demonstrated his engine running on peanut oil. Petroleum supplies were plentiful in the early to mid twentieth century, making petroleum-based fossil fuels more cost effective than vegetable oil. But more recently, the limited supply and large demand on fossil fuels have caused vegetable oil to be an economically viable option. Advantageously, vegetable oil is a renewable fuel source that can be produced domestically, and which provides superior lubrication qualities for an engine. When vegetable oil is combusted in a diesel engine, the emissions typically are dramatically decreased for nearly all areas compared to petroleum-based diesel emissions. For example, carbon dioxide is first removed from the atmosphere by plants, is stored in the vegetable oil in carbon chains, and then is returned to the atmosphere when the vegetable oil is burned in a diesel engine, resulting in zero net CO2 emissions. Vegetable oil is less flammable, less toxic, and requires less energy and resources to refine than any other fuel source.
A significant difficulty often encountered with running modern diesel engines on vegetable oil, however, lies in the viscosity of vegetable oil, which is typically higher than the viscosity of petroleum-based diesel fuels. In order to run vegetable oil in a diesel engine and maintain longevity of the engine and injection pump, the vegetable oil typically must be heated before it enters the engine. This allows the oil to achieve complete combustion, reduces carbon build-up on the injectors, eases the strain on the fuel injection pump, and allows the vegetable oil to flow through the fuel filters at high flow rates. There are many methods that can be used to heat the vegetable oil. One method is through the use of electrical heating elements. This method is effective but puts additional strain on the vehicle's alternator, and also may be more prone to shortages or failure due to electrical malfunction and limited heater element life. Another method is to utilize a self-regulated system that stores engine heat and can be routed to heat the vegetable oil at safe temperatures, which is the engine coolant system. A significant drawback to this method is that it typically requires close contact between the vegetable oil and the engine coolant. There are serious deleterious effects if these systems exchange fluids, which could lead to permanent engine or injection pump failure.
Thus it can be seen that needs exist for improved systems, methods and components for utilizing vegetable oil or other materials with temperature-dependent viscosity as the fuel for a diesel engine. It is to the provision of improved systems, methods and components meeting this and other needs that the present invention is primarily directed.